The present invention is directed to pavement construction, including the formation, repair and resurfacing of roadways, runways, footways, parking areas and other paved surfaces, and more particularly, to material compositions and methods for use in conjunction therewith.
Paved surfaces made from cementitious and asphaltic compositions are constantly being constructed for a variety of applications. Pavement construction further entails the periodic repair, resurfacing and upgrading of such surfaces. Ever increasing usage, adverse environmental conditions and progressive aging all contribute to pavement damage and degradation. Problems are particularly apt to arise at asphalt-cement interfaces. The thermal coefficients of portland cement and asphaltic pavement are vastly different and differential contraction and expansion opens cracks wherever the two join, exposing sub-base materials to weather.
Historically, asphalt has been used as a preferred construction material in the formation, repair and resurfacing of pavement surfaces. Prior to the 1973 "oil embargo," asphalt paving oils were rich with hydrocarbon "light-ends" which provided ductility and a sticky quality needed in asphalt pavement construction and repair preparations. This was due primarily to inefficient oil refining technologies. With the fuel shortages brought on during the embargo, oil prices rose to $60 a barrel at the pump. These conditions led to the improvement of refining technologies and the ability to obtain more light-end fuel from the crude oil. The once rich refinery bottoms used for asphalt paving oil have become a dry, brittle residue.
Current asphalt products for pavement construction lack the adhesive qualities of prior compositions and require the addition of tack oil to effectuate a satisfactory adhesive bond. Pavement replacement and repair is required more often as service life declines and surfaces fail more rapidly, primarily due to dry brittle oil. There are also a number of historical disadvantages associated with asphalt construction, particularly in the repair of existing surfaces. Most asphalt handling equipment is large, expensive and slow to respond to small jobs. A typical pot hole patch in a parking lot may carry a $1000.00 minimum. Consequently, several pot holes may be allowed to occur before repairs are contracted.
Utility contractors must often delay projects until a pavement repair sub-contractor can be scheduled. This is not only costly in delays and time, but lets sub-contractors dictate which jobs can be completed and when. One of the major factors in many communities is the availability of asphalt material. Often in small or remote towns, the construction work must be scheduled when an asphalt batch plant and rock crusher is in the vicinity, which may be years between large construction contracts in the area.
Emergency construction caused by floods, earthquakes, traffic accidents, etc., also requires rapid attention. However, construction material may not always be available. Seasonal conditions such as weather and traffic concentrations also play a role in pavement construction. In North America and Europe, the freeze-thaw cycle in spring and fall generates the most pavement repair activity. Safety concerns necessitating work in cold, wet conditions generally result in temporary surfaces which last less than two months.
Accordingly, a need exists for an asphalt alternative for pavement construction, including the formation, repair and resurfacing of such surfaces. Preferably, the pavement construction material would be warehouse available, portable, dependable, require no tack oil or other adhesive additives and be applicable in cold, damp, remote situations with inexpensive hand tools.